package com.decent.util;

import lombok.extern.slf4j.Slf4j;
import org.apache.commons.codec.binary.Base64;
import org.apache.commons.lang3.StringUtils;
import org.springframework.data.redis.core.RedisTemplate;

import javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import java.security.*;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.TimeUnit;

/**
 * rsa加密工具类
 *
 * @author wangyx
 */
@Slf4j
public final class RsaUtils {

    public static void main(String[] args) throws Exception {
        Map<String, Key> stringKeyMap = initKey();
        String publicKey = getPublicKey(stringKeyMap);
        String privateKey = getPrivateKey(stringKeyMap);
        String inputStr = "MANUTD is the greatest club in the world";
        byte[] encodedData = encryptByPublicKey(inputStr, publicKey);
        byte[] decodedData = decryptByPrivateKey(encodedData,
                privateKey);
        String outputStr = new String(decodedData);
        System.err.println("加密前: " + inputStr + "\n\r" + "解密后: " + outputStr);
    }

    private static final String KEY_ALGORITHM = "RSA";
    private static final String SIGNATURE_ALGORITHM = "MD5withRSA";
    private static final String PUBLIC_KEY = "RSAPublicKey";
    private static final String PRIVATE_KEY = "RSAPrivateKey";

    private static byte[] decryptBase64(String key) {
        return Base64.decodeBase64(key);
    }

    public static String encryptBase64(byte[] bytes) {
        return Base64.encodeBase64String(bytes);
    }

    /**
     * 用私钥对信息生成数字签名
     *
     * @param data       加密数据
     * @param privateKey 私钥
     * @return 数字签名
     * @throws Exception 初始化key工厂、工厂获取公钥异常、初始化签名算法异常、生成签名异常
     */
    public static String sign(byte[] data, String privateKey) throws Exception {
        // 解密由base64编码的私钥
        byte[] keyBytes = decryptBase64(privateKey);
        // 构造PKCS8EncodedKeySpec对象
        PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);
        // KEY_ALGORITHM 指定的加密算法
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        // 取私钥匙对象
        PrivateKey priKey = keyFactory.generatePrivate(pkcs8KeySpec);
        // 用私钥对信息生成数字签名
        Signature signature = Signature.getInstance(SIGNATURE_ALGORITHM);
        signature.initSign(priKey);
        signature.update(data);
        return encryptBase64(signature.sign());
    }

    /**
     * 校验数字签名
     *
     * @param data      加密数据
     * @param publicKey 公钥
     * @param sign      数字签名
     * @return 校验成功返回true 失败返回false
     * @throws Exception 初始化key工厂、工厂获取公钥异常、初始化签名算法异常、验证异常
     */
    public static boolean verify(byte[] data, String publicKey, String sign) throws Exception {
        // 解密由base64编码的公钥
        byte[] keyBytes = decryptBase64(publicKey);
        // 构造X509EncodedKeySpec对象
        X509EncodedKeySpec keySpec = new X509EncodedKeySpec(keyBytes);
        // KEY_ALGORITHM 指定的加密算法
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        // 取公钥匙对象
        PublicKey pubKey = keyFactory.generatePublic(keySpec);
        Signature signature = Signature.getInstance(SIGNATURE_ALGORITHM);
        signature.initVerify(pubKey);
        signature.update(data);
        // 验证签名是否正常
        return signature.verify(decryptBase64(sign));
    }

    /**
     * 解密<br>
     * 用私钥解密
     *
     * @param data 密文字节组
     * @param key  私钥
     * @return 明文字节组
     * @throws Exception 解密异常
     */
    private static byte[] decryptByPrivateKey(byte[] data, String key) throws Exception {
        // 对密钥解密
        byte[] keyBytes = decryptBase64(key);
        // 取得私钥
        PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        Key privateKey = keyFactory.generatePrivate(pkcs8KeySpec);
        // 对数据解密
        Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
        cipher.init(Cipher.DECRYPT_MODE, privateKey);
        return cipher.doFinal(data);
    }

    /**
     * 解密<br>
     * 用私钥解密
     *
     * @param data 密文
     * @param key  私钥
     * @return 明文字节组
     * @throws Exception 解密异常
     */
    @SuppressWarnings("unused")
    public static byte[] decryptByPrivateKey(String data, String key) throws Exception {
        return decryptByPrivateKey(decryptBase64(data), key);
    }

    /**
     * 解密<br>
     * 用公钥解密
     *
     * @param data 密文字节组
     * @param key  公钥
     * @return 明文字节组
     * @throws Exception 解密异常
     */
    @SuppressWarnings("unused")
    public static byte[] decryptByPublicKey(byte[] data, String key) throws Exception {
        // 对密钥解密
        byte[] keyBytes = decryptBase64(key);
        // 取得公钥
        X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        Key publicKey = keyFactory.generatePublic(x509KeySpec);
        // 对数据解密
        Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
        cipher.init(Cipher.DECRYPT_MODE, publicKey);
        return cipher.doFinal(data);
    }

    /**
     * 加密<br>
     * 用公钥加密
     *
     * @param data 原文
     * @param key  公钥
     * @return 密文字节组
     * @throws Exception 加密异常
     */
    public static byte[] encryptByPublicKey(String data, String key) throws Exception {
        // 对公钥解密
        byte[] keyBytes = decryptBase64(key);
        // 取得公钥
        X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        Key publicKey = keyFactory.generatePublic(x509KeySpec);
        // 对数据加密
        Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
        cipher.init(Cipher.ENCRYPT_MODE, publicKey);
        return cipher.doFinal(data.getBytes());
    }

    /**
     * 加密<br>
     * 用私钥加密
     *
     * @param data 原文
     * @param key  私钥
     * @return 密文字节组
     * @throws Exception 加密异常
     */
    @SuppressWarnings("unused")
    public static byte[] encryptByPrivateKey(byte[] data, String key) throws Exception {
        // 对密钥解密
        byte[] keyBytes = decryptBase64(key);
        // 取得私钥
        PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        Key privateKey = keyFactory.generatePrivate(pkcs8KeySpec);
        // 对数据加密
        Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
        cipher.init(Cipher.ENCRYPT_MODE, privateKey);
        return cipher.doFinal(data);
    }

    /**
     * 取得私钥
     *
     * @param keyMap 密钥对
     * @return 私钥字符串
     */
    private static String getPrivateKey(Map<String, Key> keyMap) {
        Key key = keyMap.get(PRIVATE_KEY);
        return encryptBase64(key.getEncoded());
    }

    /**
     * 取得公钥
     *
     * @param keyMap 密钥对
     * @return 公钥字符串
     */
    public static String getPublicKey(Map<String, Key> keyMap) {
        Key key = keyMap.get(PUBLIC_KEY);
        return encryptBase64(key.getEncoded());
    }

    /**
     * 初始化密钥
     *
     * @return 秘钥对
     * @throws Exception 秘钥初始化失败异常
     */
    public static Map<String, Key> initKey() throws Exception {
        KeyPairGenerator keyPairGen = KeyPairGenerator.getInstance(KEY_ALGORITHM);
        keyPairGen.initialize(1024);
        KeyPair keyPair = keyPairGen.generateKeyPair();
        Map<String, Key> keyMap = new HashMap<>(4);
        // 公钥
        keyMap.put(PUBLIC_KEY, keyPair.getPublic());
        // 私钥
        keyMap.put(PRIVATE_KEY, keyPair.getPrivate());
        return keyMap;
    }


}